I guess another reason might be investment. How much would a mint 'kept in the case' 1950's LP go for now? Or a Brazillian Rosewood Modern Eagle in 50 years time?
Guitars are quite possibly a better investment than the stock exchange :)
Yeah, but only if you buy the "right" ones and hold on to them long enough.
(That's ignoring the current state of the economy - right now almost anything is probably a better/safer investment than the Stock Exchange -
unless you have money to burn and aren't averse to taking risks).
If you really wanted to go the investor-collector route, you'd either need loads of money
now, to buy valuable pieces and hope they get even more valuable, or you'd have to put in some pretty hard work scouring the planet for those urban-legend guitars that have been kept in lofts by old ladies since their husbands died 40 or 50 years ago.
Guitars in general are a rubbish investment. In the last 25 years I've sold 45 guitars and lost about 10 grand on them. Better to buy 'em because you like 'em, and if one or two appreciate in value it's an added bonus. :)